Re: [Last-Call] Opsdir last call review of draft-ietf-quic-version-negotiation-10

[David Schinazi <[e-mail]>]

Thanks! Responses inline.
David

On Sat, Oct 1, 2022 at 6:42 AM Qin Wu <[e-mail]> wrote:

> Hi, David:
>
> Thanks for taking my comments into account, one more comment to version negotiation mechanism, do you think a single error code “TRANSPORT_PARAMETER_ERROR
>
> ” is sufficient, do you need to distinguish different reasons for version
> negotiation failure, if I am wrong, please correct me.
>
> please see follow up comment inline.
>

We currently use two errors in this document:
* TRANSPORT_PARAMETER_ERROR means the transport parameter was invalid
* VERSION_NEGOTIATION_ERROR means we detected a downgrade attack
We believe this to be enough to differentiate failure cases. There is also
an error string available from QUIC for debugging purposes.

*发件人:* David Schinazi [mailto:[e-mail]]
> *发送时间:* 2022年10月1日 6:37
> *收件人:* Qin Wu <[e-mail]>
> *抄送:* [e-mail]; [e-mail];
> [e-mail]; [e-mail]
> *主题:* Re: Opsdir last call review of
> draft-ietf-quic-version-negotiation-10
>
>
>
> Hi Qin, thank you for your comments, responses inline.
>
>
>
> Note to other WG members: PR 127 is completely editorial but 128 does add
>
> some RFC 2119 language that was previously implicit, please double-check
> my work.
>
>
>
> Thanks,
>
> David
>
>
>
> On Fri, Sep 30, 2022 at 5:48 AM Qin Wu via Datatracker <[e-mail]>
> wrote:
>
> Minor Issues:
>
> 1. Section 4 introduce verson downgrade term [Qin]What the version
> downgrade is? I
> feel confused, does it mean when I currently use new version, I should not
> fall
> back to the old version? Can you explain how version downgrade is different
> from version incompatible? It will be great to give a definition of version
> downgrade in the first place or provide an example to explain it?
>
>
>
> It's a pretty common term of art in versioned protocols but I've defined
> it in Section 4.
>
> https://github.com/quicwg/version-negotiation/pull/127
>
> [Qin] Thanks, the proposed change looks good.
>

Thanks.

> 2. Section 9
> said: " The requirement that versions not be assumed compatible mitigates
> the
> possibility of cross-protocol attacks, but more analysis is still needed
> here."
> [Qin] It looks this paragraph is incomplete, what else analysis should we
> provide to make this paragraph complete?
>
>
>
> The paragraph is complete. It acknowledges the potential for
> cross-protocol attacks
>
> and encourages more research in this area.
>
> [Qin]: If that is the case, I suggest to add some text to explain this
> analysis is not in the scope of this document.
>

I've added "That analysis is out of scope for this document."
https://github.com/quicwg/version-negotiation/commit/3b9f4e044572a81c39bedc6b8d77cedd35fbd355


> 3. Section 10 [Qin]: I am not clear
> why not request permanent allocation of a codepoint in the 0-63 range
> directly
> in this document. In my understanding, provisional codepoint can be
> requested
> without any dependent document? e.g., Each vendor can request IANA for
> Vendor
> specific range. Secondly, if replacing provisional codepoint with permanent
> allocation, requires make bis for this document, I don't think it is
> reasonable.
>
>
>
> The IANA section means that when the IESG approves the document, we will
>
> modify the document to select a permanent 0-63 codepoint before or during
>
> AUTH48. There will be no need for a bis document.
>
> [Qin]:Thank for clarification, I am wondering why not request both
> codepoints at the same time,
>
> I feel the current text in section 10 for codepoint request is temporary
> text and subject to change, would it be great to make these text normative,
>
> Which doesn’t need to make another request using one more document.
>

This will all happen before publication. This pattern allows us to only
reserve low codepoints when we know the protocol will no longer change.


> Nits:
>
> 1. Section 2 said: " For instance, if the client initiates a
> connection with version A and the server starts incompatible version
> negotiation and the client then initiates a new connection with .... "
> [Qin]Can
> the client starts incompatible version negotiation? if not, I think we
> should
> call this out, e.g., using RFC2119 language.
>
>
>
> Good catch, this was an implicit assumption. I made it explicit with 2119
> text:
>
> https://github.com/quicwg/version-negotiation/pull/128
>
>
>
> 2. Section 2, last paragraph [Qin]
> This paragraph is a little bit vague to me, how do we define not fully
> support?
> e.g., the server can interpret version A, B,C, but the server only fully
> implements version A,B, regarding version C, the server can read this
> version,
> but can not use this version, in other words, it is partially implemented,
> is
> my understanding correct?
>
>
>
> Your understanding is correct. Do you have suggestions for better wording?
>
> [Qin]:I suggest to consider the relation between fully supported and
> negotiated versioned, offered version, accepted version.
>
> If my understanding is correct, parsing the first flight of a given
> version means you can negotiate a new version between the client
>
> And the server ,if the negotiated version is not accepted version or not
> agreed by both the client and server,we can not use the negotiated
>
> Version to establish the connection, not less than communicate the data
> packet using this version.
>
> Hope this helps you find better wording.
>

I'm sorry, but the WG has considered the relationship between all these
concepts and they need to all exist to avoid some tricky race conditions.

3.Section 2.1 the new term "offered version" [Qin]
> Can you add one definition of offered versions in section 1.2, terminology
> section? To be honest, I still not clear how offered version is different
> from
> negotiated version? Also I suggest to add definitions of accepted version,
> deployed version as well in section 1.2? Too many terminologies, hard to
> track
> them in the first place.
>
>
>
> Those terms are introduced with a reference to Section 5 that very clearly
>
> defines them. Duplicating those definitions in Section 1.2 would make the
>
> document less clear in my opinion.
>
> [Qin] Okay, my logic is you should make different xx version definition in
> the first place to help reader who has no quic background better understand
>
> The mechanism proposed in this draft.
>
> I will leave this up to you, no strong opinion on this.
>

Thanks.

4. Section 6 said: " it is possible for some
> application layer protocols to not be able to run over some of the offered
> compatible versions. " [Qin]I believe compatible versions is not
> pertaining to
> any application layer protocol, if yes,
>  s/compatible versions/compatible QUIC versions
>
>
>
> Compatible versions are defined as referring to QUIC versions. My apologies
>
> but I think the existing text is clearer.
>
> [Qin]Good.
>

Thanks .

> 5.Section 7.1 said:
> "For example, that could be accomplished by having the server send a Retry
> packet in the original
>  version first thereby validating the client's IP address before"
> [Qin] Is Version first Version 1? If the answer is yes, please be
> consistent
> and keep using
>  either of them instead of inter-exchange to use them.
>  s/version first/version 1
>
>
>
> You're misunderstanding this sentence, I've moved the word first to avoid
> the confusion:
>
>
> https://github.com/quicwg/version-negotiation/commit/e1ca5b749e2ea2347db7d8353bc2f9cc770ae354
>
>
>
> [Qin]: Thanks. I am clear for this comment.
>

Thanks.